If it turns out to not be the kernel, would it be a safe bet to assume it's hardware related?

Or do you strongly suspect that it is a software issue?

Not that experienced with samsung devices..I*m a HTC guys.
On htc devices hboot (bootloader version) and firmware could me another culprit. Since there are parts, like bootloader/firmware we can't really debug it can be always software related imo.
Only way for us to tell if not is to revert to a previous base where it worked...is it possible to downgrade on samsung?

Not that experienced with samsung devices..I*m a HTC guys.
On htc devices hboot (bootloader version) and firmware could me another culprit. Since there are parts, like bootloader/firmware we can't really debug it can be always software related imo.
Only way for us to tell if not is to revert to a previous base where it worked...is it possible to downgrade on samsung?

What happens when you try to wake it by plugging in charger?
Next, try and play a song and put it on repeat single. When it sleeps, does music keep playing?
Also try and set alarm clock to see if it wakes device after it sleeps.
If it was my machine, I would backup my data and clear all caches and partitions in recovery and reflash firmware after verifying the checksum.

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